GEOLOGICAL SURVEY OF THE TERRITORIES. 427 



from the vertebra which supports the last dorsal spine. The scales are 

 of about the same size as those of the A. squamifrons. Dorsal region 

 scarcely convex, (in the specimen concave through slight distortion.) 



M. 



Length of vertebral column to operculum 0.07 



Depth at last anal ray 019 



Length of last dorsal spine 017 



Another specimen lacks the head and caudal fin, but displays charac- 

 ters at variance with those of Asineops squamisfrons as above noted. The 

 interneural bones of the anal spines are fasciculate, the median longer 

 than those in front and behind. 



The ventral outline is convex, and the general form shortened. Eadii 

 A. % II, 14 j D. I 12-13. There are only 13 vertebrae behind the last 

 anal spine. 



M. 

 Length of vertebral column from vertebra supporting last A. spine . 0.033 

 Depth at second soft A. ray 027 



From the Green Eiver shales; from the collection of Lucius E. Eick- 

 secker. 



EEISMATOPTEEUS, (Cope ;) genus nov. 



Dorsal and anal fins with two strong supporting spines in front ; no 

 other interhsemal spines than those supporting them. Dorsal fin above 

 the anterior median or posterior abdominal region. Yentrals origin- 

 ating in front of or opposite to the origin of the dorsal. Pubes sending 

 a limb upward, which is in contact with the inferior post-clavicle. 

 Teeth minute or ? wanting. Caudal fin bifurcate. 



I originally referred a species of this genus to the Gyprinodontidce 

 and provisionally to the genus Gyprinodon. The species may belong to 

 that family, as the characters are generally similar. The arc of the 

 mouth is formed by the premaxillary bone, and the ventral fins have a 

 rather anterior position, and the caudal is furcate; the scales are cycloid. 

 The strength of the spinous fin radii and supporting interhsemal spines 

 attracted my attention, and on careful examination I observe other 

 approximations to the type of Asineops and the Aphredodiridce. The 

 inferior post-clavicle is very long and styliform, as in the latter genus, 

 and the pubic bones are slender and directed upward so as to reach 

 the post-clavicles. In one specimen there appears to be an anteriorly 

 directed pubic limb, but this does not exist in other specimens. The 

 pubes do not reach the clavicles as in true Physoclysti. As the genus is 

 thus different from Gyprinodon, Fundulus, &c, I name it as above. 



ERISMATOPTERUS RICKSECKERI, (COPE;) Sp. nOV. 



Length, three to four inches ; head, large. Vertebrae, D. 13, C. 16= 

 29, ten between the interneural bone supporting the first dorsal ray, and 

 the first interhsemal supporting the first anal ray. There are only 

 seven in this position in U. lemtus. Anterior dorsal ray anterior to the 

 point half way between end of muzzle and end of vertebral column. 

 Branchiostegal radii, five distinguishable. Head stout, mouth terminal, 

 orbit equal length of muzzle; maxillary bone reaching line of middle of 

 orbit. Scales small with numerous concentric and no radiating grooves. 

 Ein radii D. VII, 8, (last split;) C. 8—19—8; A. II, 9; V. 7; P. 15. 



